He entrusted the Gospel to us because He saw our fitness. He saw that, with the help of grace, we would receive the holy thing entrusted to us in purity, preserve it in purity, and hand it on to others in purity.
We would do this without admixture from the corruption of our mind and heart. Theophylact says: "God tested us and chose us, in order to entrust us with the Gospel."
He would not have chosen us if He had not recognized us as worthy. If there had been something bad in us, God would not have recognized us as fit and well-proven.
The proof of such worthiness is that the Gospel has been entrusted to us, as Chrysostom says. Yet Saint Paul's purpose in mentioning this here is not to remind others of his own dignity.
It is to assure them of his faithfulness to God's command. Since such trust has been shown to us, we cannot prove unfaithful. As it was entrusted to us, and as it was commanded when entrusted, so we speak.
That is, we speak in the same spirit, according to the same norm and thought. The preaching of the Gospel fully corresponds to the trust.
God approved us and entrusted the Gospel to us. As He approved us, so we remain. Chrysostom says: "We speak as is fitting for those tested by God and recognized as worthy to preach the Gospel."
The conclusion is this: therefore believe our word as the word of God. We speak to you not from any of the causes indicated and rejected above. We speak what is God's, by God's command, without any admixture of anything blameworthy before God.
"As we were approved, so we speak, not as pleasing men, but God who tests our hearts." We do not have in mind, he says, pleasing men. All our care is to prove pleasing to God, who tests the hearts.
Theodoret says: "We did not appoint ourselves teachers. Rather, the Gospel was entrusted to us by God. Therefore we both speak and do everything as before God as witness, for we know that not one movement of the soul is hidden from Him."
Although Saint Paul says that they only strive to show their work pleasing to God, it is evident that they nourish confidence that it is truly so.
Their conscience witnesses that they are faithful in everything to the One who entrusted them, and that they act entirely according to His intentions and desires.
By this the Apostle forestalls an accusation harmful to the success of the Gospel, namely that they act from man-pleasing. In that case, suspicion of bending the truth is always appropriate.
But this is impossible when they act before God in order to please Him. God sees this unchanging faithfulness, and we zealously strive with fear to show it to Him.
We serve as though before His face, lest He remove us from the work because of unfaithfulness. If He does not remove us, this means He sees us as faithful.
The conclusion here is the same: therefore do not waver in faith toward our word, for it is fully what God Himself is pleased for it to be.
By the men whom Saint Paul denies pleasing, one may understand people who would have led them into error and persuaded them to spread their false teaching. Or one may understand people who contrived some plot and instructed them to act according to their plan.
One may also understand those to whom the Gospel is preached. Then he shows that they do not adapt themselves to their desires, but speak the truth of God directly, without being stopped by the fact that it may be unpleasant to the hearers; compare Gal 1:10.